What does this command mean at the end of the Dockerfile?

Question

bash

at the end of the Dockerfil, the ENTRYPOINT script runs, which says the following:

script.sh
------------------------------------ -------------------------------------------------- -------

sleep infinity & wait $!

well, the first is clear, but why the second part of wait $! ?

Answer 1

$! - one of the "magic" bash variables, contains the pid of the last process
wait - I think it's understandable

Answer 2

I think this line doesn't make sense. An endless slip in the background, and waiting for the background task to complete.
Together - it is difficult to understand what specific meaning in such a combination.